diff --git a/public/admin/audit-analytics.html b/public/admin/audit-analytics.html
index 1e0de208..8df4f834 100644
--- a/public/admin/audit-analytics.html
+++ b/public/admin/audit-analytics.html
@@ -6,6 +6,7 @@
   <title>Audit Analytics | Tractatus Admin</title>
   <link rel="icon" type="image/svg+xml" href="/favicon.svg">
   <link rel="stylesheet" href="/css/tailwind.css">
+  <script src="/js/admin/auth-check.js"></script>
   <style>
     html { scroll-behavior: smooth; }
 
diff --git a/public/admin/blog-curation.html b/public/admin/blog-curation.html
index 3c612362..14e29efd 100644
--- a/public/admin/blog-curation.html
+++ b/public/admin/blog-curation.html
@@ -5,6 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>Blog Curation | Tractatus Admin</title>
   <link rel="stylesheet" href="/css/tailwind.css?v=1759833751">
+  <script src="/js/admin/auth-check.js"></script>
 </head>
 <body class="bg-gray-50">
 
diff --git a/public/admin/claude-md-migrator.html b/public/admin/claude-md-migrator.html
index 4b272fa3..a3368cad 100644
--- a/public/admin/claude-md-migrator.html
+++ b/public/admin/claude-md-migrator.html
@@ -5,6 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>CLAUDE.md Migration Wizard - Tractatus Admin</title>
   <link href="../css/tailwind.css" rel="stylesheet">
+  <script src="/js/admin/auth-check.js"></script>
 </head>
 <body class="bg-gray-100">
   <!-- Navigation -->
diff --git a/public/admin/dashboard.html b/public/admin/dashboard.html
index a8a9ca77..540b60a0 100644
--- a/public/admin/dashboard.html
+++ b/public/admin/dashboard.html
@@ -5,6 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <title>Admin Dashboard | Tractatus Framework</title>
   <link rel="stylesheet" href="/css/tailwind.css?v=1759833751">
+  <script src="/js/admin/auth-check.js"></script>
 </head>
 <body class="bg-gray-50">
 
diff --git a/public/admin/login.html b/public/admin/login.html
index a667d9b5..fb9f1199 100644
--- a/public/admin/login.html
+++ b/public/admin/login.html
@@ -73,7 +73,7 @@
         <!-- Helper Text -->
         <div class="text-center">
           <p class="text-sm text-gray-600">
-            Default credentials: <code class="text-xs bg-gray-200 px-2 py-1 rounded">admin@tractatus.local</code> / <code class="text-xs bg-gray-200 px-2 py-1 rounded">tractatus123</code>
+            Enter your admin credentials to continue
           </p>
         </div>
       </form>
diff --git a/public/admin/project-manager.html b/public/admin/project-manager.html
index 1b0079dc..2751ad71 100644
--- a/public/admin/project-manager.html
+++ b/public/admin/project-manager.html
@@ -6,6 +6,7 @@
   <title>Project Manager | Multi-Project Governance</title>
   <link rel="icon" type="image/svg+xml" href="/favicon.svg">
   <link rel="stylesheet" href="/css/tailwind.css?v=1760127701">
+  <script src="/js/admin/auth-check.js"></script>
 </head>
 <body class="bg-gray-50">
 
diff --git a/public/admin/rule-manager.html b/public/admin/rule-manager.html
index b4d7521c..e9040775 100644
--- a/public/admin/rule-manager.html
+++ b/public/admin/rule-manager.html
@@ -6,6 +6,7 @@
   <title>Rule Manager | Multi-Project Governance</title>
   <link rel="icon" type="image/svg+xml" href="/favicon.svg">
   <link rel="stylesheet" href="/css/tailwind.css?v=1760127701">
+  <script src="/js/admin/auth-check.js"></script>
 </head>
 <body class="bg-gray-50">
 
diff --git a/public/js/admin/auth-check.js b/public/js/admin/auth-check.js
new file mode 100644
index 00000000..615f5e77
--- /dev/null
+++ b/public/js/admin/auth-check.js
@@ -0,0 +1,135 @@
+/**
+ * Admin Authentication Check Utility
+ * Protects admin pages by redirecting unauthenticated users to login
+ *
+ * Usage: Include at top of every admin page HTML:
+ * <script src="/js/admin/auth-check.js"></script>
+ */
+
+(function() {
+  'use strict';
+
+  // Skip auth check on login page itself
+  if (window.location.pathname === '/admin/login.html') {
+    return;
+  }
+
+  /**
+   * Check if user has valid authentication token
+   */
+  function checkAuthentication() {
+    const token = localStorage.getItem('admin_token');
+
+    // No token found - redirect to login
+    if (!token) {
+      redirectToLogin('No authentication token found');
+      return false;
+    }
+
+    // Parse token to check expiration
+    try {
+      const payload = parseJWT(token);
+      const now = Math.floor(Date.now() / 1000);
+
+      // Token expired - redirect to login
+      if (payload.exp && payload.exp < now) {
+        localStorage.removeItem('admin_token');
+        redirectToLogin('Session expired');
+        return false;
+      }
+
+      // Check if admin role
+      if (payload.role !== 'admin' && payload.role !== 'moderator') {
+        redirectToLogin('Insufficient permissions');
+        return false;
+      }
+
+      // Token valid
+      return true;
+
+    } catch (error) {
+      console.error('Token validation error:', error);
+      localStorage.removeItem('admin_token');
+      redirectToLogin('Invalid authentication token');
+      return false;
+    }
+  }
+
+  /**
+   * Parse JWT token without verification (client-side validation only)
+   */
+  function parseJWT(token) {
+    const parts = token.split('.');
+    if (parts.length !== 3) {
+      throw new Error('Invalid token format');
+    }
+
+    const payload = parts[1];
+    const decoded = atob(payload.replace(/-/g, '+').replace(/_/g, '/'));
+    return JSON.parse(decoded);
+  }
+
+  /**
+   * Redirect to login page with reason
+   */
+  function redirectToLogin(reason) {
+    const currentPath = encodeURIComponent(window.location.pathname + window.location.search);
+    const loginUrl = `/admin/login.html?redirect=${currentPath}&reason=${encodeURIComponent(reason)}`;
+
+    // Show brief message before redirect
+    document.body.innerHTML = `
+      <div style="display: flex; align-items: center; justify-content: center; height: 100vh; font-family: system-ui, -apple-system, sans-serif;">
+        <div style="text-align: center;">
+          <svg style="width: 64px; height: 64px; margin: 0 auto 16px; color: #3B82F6;" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+            <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M12 15v2m-6 4h12a2 2 0 002-2v-6a2 2 0 00-2-2H6a2 2 0 00-2 2v6a2 2 0 002 2zm10-10V7a4 4 0 00-8 0v4h8z"/>
+          </svg>
+          <h2 style="font-size: 20px; font-weight: 600; color: #111827; margin-bottom: 8px;">Authentication Required</h2>
+          <p style="color: #6B7280; margin-bottom: 16px;">${reason}</p>
+          <p style="color: #9CA3AF; font-size: 14px;">Redirecting to login...</p>
+        </div>
+      </div>
+    `;
+
+    setTimeout(() => {
+      window.location.href = loginUrl;
+    }, 1500);
+  }
+
+  /**
+   * Add authentication headers to fetch requests
+   */
+  function getAuthHeaders() {
+    const token = localStorage.getItem('admin_token');
+    return {
+      'Authorization': `Bearer ${token}`,
+      'Content-Type': 'application/json'
+    };
+  }
+
+  /**
+   * Handle API authentication errors
+   */
+  function handleAuthError(response) {
+    if (response.status === 401 || response.status === 403) {
+      localStorage.removeItem('admin_token');
+      redirectToLogin('Session expired or invalid');
+      return true;
+    }
+    return false;
+  }
+
+  // Run authentication check immediately
+  checkAuthentication();
+
+  // Export utilities for admin pages to use
+  window.AdminAuth = {
+    getAuthHeaders,
+    handleAuthError,
+    checkAuthentication,
+    redirectToLogin
+  };
+
+  // Periodically check token validity (every 5 minutes)
+  setInterval(checkAuthentication, 5 * 60 * 1000);
+
+})();
